This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to 19985567 filed in Norway on Nov. 27, 1998; the entire content of which is hereby incorporated by reference.
The present invention relates to telecommunications. More particularly, and not by way of limitation, the present invention is directed to a method for extending the use of SIP (Session Initiation Protocol).
More specifically the present invention relates to such a method for facilitating the charging of such SIP connections.
The Problem
SIP, as described in Handley et. al., xe2x80x9cSIP: Session Initiation Protocolxe2x80x9d, is a competitive protocol to H.323, which is described in ITU-T, xe2x80x9cdocument packet-based multimedia communications systemsxe2x80x9d, to allow Multimedia applications to operate over the IP protocol. The Internet Engineering Task Force (IETF) has standardized SIP. The latest version of SIP is currently only a draft, provided by the Multi-party Multimedia Session Control (MMUSIC) working group (WG) in IETF.
The SIP protocol supports most of the features of the H.323 protocol, but it is simpler in respect to a number of different messages. The fact that SIP is simpler than H.323 makes it easier to make a SIP-compliant end-point than an H.323-compliant end-point. New development tools and programming languages also make it easier to control media-interferences. This also makes it easier to make a multi-media end-point. When making an end-point, it is also easy to add additional logic and functionality beyond what is stated in the standard.
One of the methods for performing charging for SIP or H.323 conversations is to place the charging logic inside a SIP server or a gatekeeper (H.323), as illustrated in FIG. 1.
One of the problems with SIP is that it does not have support for a typical xe2x80x9ccontinue callxe2x80x9d message. Another problem is that SIP-complaint end-points could send the CLOSE message directly to each other instead of via a SIP server. This makes it difficult to support charging for SIP conversations. The reason for this is that the media traffic is not sent via the gatekeeper or the SIP server, and it is difficult to know when the conversation is closed.
Known Solutions
In the H.323 standard there is support for a xe2x80x9ccontinue callxe2x80x9d message. In the Q.931 signaling protocol part of H.323, which is described in the ITU-T standard, the message is called xe2x80x9cstatus inquiryxe2x80x9d In the RAS part of H.323 the IPR message can be used for the same purpose. In H.323 it is also required that the end-points send the xe2x80x9cclosed conversationxe2x80x9d message via the gatekeeper (if a gatekeeper-routed call model is used).
An object of he present invention is to provide a method by which the use of SIP (Session Initiation Protocol) is extended in a rational and expedient manner.
A further object of the present invention is to provide a method by which it is radially observed when a conversation between two end-points is concluded.
A still further object of the present invention is to provide a method by which charging for SIP conversations can be stipulated in a very accurate and expedient manner.
A still further object of the present invention is to provide a method by which the message xe2x80x9ccontinue callxe2x80x9d is favourably supported by a corresponding SIP server.
These objects are achieved in a method as stated in the preamble, which is characterised by the features as stated in the characterising clause of the enclosed patent claim 1.
In other words, the present invention can be defined as an extension of the SIP protocol, the main idea of the present invention being that the missing xe2x80x9ccontinue callxe2x80x9d message is solved by sending extra INVITE messages to the SIP server.